Air conditioning installation

ABSTRACT

An air conditioning system for an air-conditioning of spaces comprises a compressor for compressing a refrigerant in a refrigerant circuit, a first heat exchanger for exchanging heat between the refrigerant and a heat reservoir, a plurality of throttles for expanding the refrigerant, a plurality of second heat exchangers for exchanging heat between the refrigerant and a heat transfer fluid in one associated heat transfer fluid circuit each, and a plurality of third heat exchangers which each are arranged in an associated space, for exchanging heat between the heat transfer fluid and indoor air of the associated space. To a second heat exchanger a throttle and a heat transfer fluid circuit with a plurality of third heat exchangers are associated.

The present invention relates to an air conditioning system for anair-conditioning of spaces of a building, a ship or another vehicle.

Air-conditioning of hotel rooms or office spaces formerly was usual onlyin luxurious hotels and in prestigious and high-quality officebuildings. Air-conditioning also increasingly is expected in hotels andoffice buildings of lower categories. For these and other reasons,smaller and smaller spaces have to be air-conditioned. At the same time,buildings are increasingly well insulated, and by outside blinds andother measures, the heat generated by solar radiation is reduced.

One consequence is that the cooling capacity required for an individualroom typically no longer amounts to 2000 W, but only 500 W to 600 W. Anindoor unit, on the other hand, typically has a power of 2000 W.

Another problem consists in that the cooling capacity of a conventionalair conditioning system only can be varied within predetermined limits.By an outdoor unit which is formed for a variable refrigerant flow, acooling capacity between about 120% and about 30% of its nominal powertypically can be provided. An even lower cooling capacity at an evenlower speed of the compressor generally is not possible, because therefrigerant then loses its properties lubricating the compressor.

When the cooling capacity picked up by the indoor units decreases belowthe minimum value of the cooling capacity provided by the outdoor unit,a too high pressure and/or a too high temperature can be obtained in therefrigerant circuit. The air conditioning system thereby can be damagedor destroyed. To avoid this, when the cooling capacity picked up by theindoor units falls below the minimum value, the outdoor unit is operatedin a clocked manner or switched on and off at intervals of few minutes.This can effect a corresponding temporal variation of the roomtemperature and a corresponding loss of convenience.

Choosing smaller outdoor units generally does not constitute a solutionfor several reasons. With decreasing nominal power of an outdoor unit,the ratio between the minimum power and the nominal power typicallyincreases, so that the minimum power does not decrease or only to asmall extent.

Furthermore, in air conditioning systems with variable refrigerant flowtechnically induced limitations exist with regard to the number of theindoor units and with regard to the power of the individual indoor unit.

JP 55-102842 A describes an air conditioning system with an outdoor unit11 outside a building. The outdoor unit 11 comprises a compressor 111, aheat exchanger 112 and a throttle 114. An indoor unit 12 is connectedwith the outdoor unit 11 via pipe conduits 120. In said outdoor unit,cooling capacity is transferred to a water circuit and excess coolingcapacity is dissipated by means of a fan 124.

An object of the present invention consists in creating an improved airconditioning system for an air-conditioning of spaces, which inparticular is suitable for generating a low cooling capacity.

This object is solved by the subject-matters of the independent claims.

Developments are indicated in the dependent claims.

Embodiments of the present invention are based on the idea to equipseveral indoor units of an air conditioning system with their ownthrottle each and by means of one heat exchanger each transfer thecooling capacity not directly from the refrigerant to indoor air, but toa heat transfer fluid, for example water or brine. By means of severalfurther heat exchangers, the cooling capacity is transferred from theheat transfer fluid to the indoor air of one or more spaces.

An air conditioning system for an air-conditioning of spaces comprises acompressor for compressing a refrigerant in a refrigerant circuit, afirst heat exchanger for exchanging heat between the refrigerant and aheat reservoir, a plurality of throttles for expanding the refrigerant,a plurality of second heat exchangers for exchanging heat between therefrigerant and a heat transfer fluid in one associated heat transferfluid circuit each, and a plurality of third heat exchangers which eachare arranged in an associated space, for exchanging heat between theheat transfer fluid and indoor air of the associated space, wherein athrottle and a heat transfer fluid circuit with a plurality of thirdheat exchangers are associated to the second heat exchanger.

The air conditioning system in particular is formed and provided for anair-conditioning or cooling and/or heating of spaces or rooms of one ormore buildings or of a ship or another vehicle.

The first heat exchanger in particular is arranged in direct spatialproximity of the compressor and together with the compressor inparticular is arranged in an outdoor unit which is arranged outside thebuilding or at an external border of the building or the ship or theother vehicle. The first heat exchanger in particular is formed andprovided for exchanging heat between the refrigerant and ambient air oran atmosphere surrounding the building, the ship or the other vehicle,or for exchanging heat between the refrigerant and ground water or anunderground of the building or water in which the ship floats.

The air conditioning system can include a plurality of second heatexchangers, to each of which a throttle and a separate heat transferfluid circuit with a plurality of third heat exchangers is associated.Each heat transfer fluid circuit can comprise one or more third heatexchangers. To one space, one or more heat exchangers from the same orfrom different heat transfer fluid circuits each can be associated.

The air conditioning system can include further heat exchangers for thedirect exchange of heat between the refrigerant and indoor air, forexample for an air-conditioning of meeting rooms, halls or other largespaces.

A throttle in particular each is arranged such that its distance to theassociated second heat exchanger is smaller or much smaller than itsdistance to the first heat exchanger. Distance each refers to the lengthof the fluid line connecting the throttle with the second heat exchangeror with the first heat exchanger. In particular, a throttle each isarranged directly adjacent to the associated second heat exchanger andin the flow line of the associated heat exchanger or based on the flowdirection of the refrigerant upstream of the associated second heatexchanger.

Interposing the heat transfer fluid circuit between the refrigerantcircuit and the indoor air can provide for dimensioning the coolingand/or heating capacity to be provided in individual spaces withindistinctly wider limits. In particular, small cooling capacities of onlyfew 100 W can be provided, which are sufficient in small and thermallywell insulated rooms of modern hotels or office buildings. Such areduced cooling capacity can effect a distinct reduction of the airmovement obtained in an air-conditioned space, which sometimes isperceived as unpleasant draft.

Refrigerants often are odorless and colorless. When a refrigerant exitsfrom an air conditioning system, it can force out the breathing air in aroom and cause choking of persons in the room. This risk can be reduceddistinctly, when it no longer is the refrigerant circuit, but only theheat transfer fluid circuit with water, brine or another non-toxic heattransfer fluid liquid under normal conditions that is guided into theindividual hotel room or into the individual office space. This cansimplify the compliance with regulations of EN 378 concerning maximumrefrigerant concentrations in interior spaces.

In that merely a part of the heat transfer fluid circuit is arranged inthe hotel room or in the office space, but the refrigerant circuit isarranged completely outside the hotel room or office space, the noiselevel also can be lowered distinctly. For example, the noise of a valveswitching in the hotel room or in the office space can be avoidedcompletely. The applicant expects a reduction of the noise level fromtypically at least 30 dB(A) to distinctly smaller values down to about21 dB(A).

The heat transfer fluid circuit has its own thermal capacity and its ownthermal inertia, which in particular results from the thermal capacityof the heat transfer fluid, the pipe conduits and other parts of theheat transfer fluid circuit. This thermal inertia of the heat transferfluid circuit can distinctly reduce the temporal variation of thecooling and/or heating capacity in a hotel room or an office space,which is obtained with a clocked operation of the outdoor unit.

In an air conditioning system with the described features, the number ofthe air-conditioned spaces can be a multiple of the number of the secondheat exchangers and the number of throttles. In the case of atechnically induced limitation of the number of throttles and secondheat exchangers, which together with a compressor and a first heatexchanger form the refrigerant circuit, a much higher number of spaceshence can be air-conditioned with the air conditioning system describedhere. Conversely, in the case of a large building the number ofcompressors and heat exchangers (in particular each combined in anoutdoor unit) can be reduced distinctly. Both can distinctly lower thecosts for the manufacture, operation and maintenance of the airconditioning system.

In an air conditioning system as it is described here, in particular thecompressor and the first heat exchanger are arranged in an outdoor unitoutside a building or a vehicle or at an external border of a buildingor a vehicle, and one throttle each and an associated heat exchanger arearranged in an indoor unit.

The indoor unit in particular is arranged inside the building or theship or the other vehicle, for example in a corridor or aisle or in astaircase. The indoor unit then is connected with the third heatexchangers in individual spaces via pipe conduits. As third heatexchangers, in particular components of so-called chiller systems can beused, which in English-speaking countries are known as fan coils and areoffered at low cost and in a wide variety.

An air conditioning system, as it is described here, in particularfurthermore comprises a reservoir for the heat transfer fluid, in orderto increase the thermal capacity.

The reservoir in particular is formed by a tank which is arranged in thevicinity of the associated second heat exchanger. Already with a smallvolume of e.g. 10 liters the reservoir can distinctly increase thethermal capacity of the heat transfer fluid circuit. In the case of aclocked operation of the compressor, a variation of the cooling capacityin the individual space thereby can be lowered below the perceptibilitylimit.

An air conditioning system, as it is described here, in particularfurthermore comprises a temperature sensor in the heat transfer fluidcircuit.

The temperature sensor in particular is arranged and formed to detectthe temperature of the heat transfer fluid in the flow line of thesecond heat exchanger. Furthermore, further sensors can be provided fordetecting the temperature, the pressure, the flow velocity, the massflow or other measurement quantities in the flow line of the second heatexchanger or at another point in a heat transfer fluid circuit. Thetemperature sensor and possibly further sensors for detectingmeasurement values can support a particularly sensitive control of theair conditioning system.

In an air conditioning system, as it is described here, in particular noheat exchanger is provided for dissipating cooling or heating capacityof the refrigerant to a medium other than the heat transfer fluid.

This also distinguishes the air conditioning system in particular fromthe above-mentioned air conditioning system as described in JP 55-102842A, in which excess cooling or heating capacity is dissipated. The airconditioning system described here hence provides for a particularlygood efficiency or a particularly good performance rating.

In an air conditioning system, as it is described here, in particularone throttle is controllable.

The controllable throttle or the controllable throttles each comprise inparticular an electronic expansion valve. The controllability of athrottle each provides for controlling the refrigerating capacity at theassociated second heat exchanger and hence an adaptation to differentvalues of the cooling capacity picked up at the associated third heatexchangers. The control of the air conditioning system as a wholethereby can be refined and the efficiency or performance rating therebycan be increased.

In an air conditioning system, as it is described here, an indoor unitis connected with the outdoor unit by means of three fluid lines andformed to withdraw heat from the heat transfer fluid in a cooling modeand to supply heat to the heat transfer fluid in a heating mode.

Several or all indoor units of the air conditioning system can beconnected with the outdoor unit by means of three fluid lines and beformed to each independently withdraw heat from the heat transfer fluidin a cooling mode and to supply heat to the heat transfer fluid in aheating mode. Switching between the cooling mode and the heating mode inparticular is effected by controlling a controllable throttle and byselecting one of two possible return lines by means of one or morevalves. The valve or valves for selecting one of two return lines can bearranged directly in the indoor unit or in an associated, but separateunit which is connected with the indoor unit via an (in particularshort) fluid line.

In particular in this aspect, too, an air conditioning system with theproperties and features described here distinctly differs from theteaching of the above-mentioned JP 55-102842 A, in which switchingbetween a cooling mode and a heating mode is not possible.

An air conditioning system, as it is described here, in particular isformed for a variable refrigerant volume flow.

By a variable or controllable refrigerant volume flow an adjustment ofthe total cooling or heating capacity provided by the air conditioningsystem is possible within a wide range.

In an air conditioning system, as it is described here, in particular athree-phase AC motor with adjustable speed is provided for driving thecompressor.

For adjusting the speed of the synchronous or asynchronous three-phaseAC motor in particular an inverter is provided, which is formed toprovide polyphase current of adjustable frequency and adjustableamplitude of the voltage and/or the current. This provides for avariation of the refrigerant volume flow and the cooling and/or heatingcapacity provided by the air conditioning system.

An air conditioning system, as it is described here, in particularfurthermore comprises a control means for detecting a total demand forcooling or heating capacity and for controlling the compressor between apredetermined minimum capacity and a predetermined maximum capacity,wherein the control means is formed to temporarily switch off thecompressor, when the total demand for cooling or heating capacity fallsbelow a predetermined threshold value.

In a separate control unit and/or in the outdoor unit and/or in one ormore indoor units, the control means in particular each includes one ormore microcontrollers or other electric or electronic analogue ordigital circuits for data processing, which by means of electric,optical or other signal lines are coupled with each other, with sensorsfor detecting temperatures, pressures, volumetric flow rates and othermeasurement values, and with one or more user interfaces. The controlmeans in particular also is provided and formed for controlling thethrottles.

In an air conditioning system with the properties and features describedhere, temporarily switching off the compressor and hence the coolingand/or heating capacity provided in the refrigerant circuit effects avariation of the cooling or heating capacity in the air-conditionedspaces, which due to the thermal capacity or inertia of the heattransfer fluid circuits can turn out to be distinctly lower than in aconventional air conditioning system.

In the following, various embodiments will be explained in detail withreference to the attached Figures, in which:

FIG. 1 shows a schematic representation of a building with an airconditioning system;

FIG. 2 shows a schematic representation of an air conditioning system;

FIG. 3 shows a schematic representation of a further air conditioningsystem.

FIG. 1 shows a schematic representation of a building 10 with an outerwall 12 and several spaces 14, 15 of different sizes. The representationin FIG. 1 in particular indicates a ground plan of a storey or floor ofthe building 10.

The building 10 comprises a large space 14, in particular an entrancearea which passes over into a corridor or an aisle between smallerseparate spaces. The spaces 15 have different sizes, in particulardifferent floor areas and/or room heights. The spaces 15 furthermore candiffer in their functions, in the sizes of the adjacent facade areas, inthe quality of the insulation to the outside, in the exposure to solarradiation, and in other properties.

The building 10 includes an air conditioning system which is shownseparately in FIGS. 2 and 3 described below and is provided with thereference numeral 20. The air conditioning system comprises an outdoorunit 30 which is attached to the outer wall 12 of the building 10 or canbe arranged close to the building 10 and spaced from the same.Furthermore, the air conditioning system comprises a plurality of indoorunits 40 which are connected with the outdoor unit 30 by a pipe conduitsystem. Expressed in other words, the outdoor unit 30 and the indoorunits 40 together with the pipe conduits connecting the same form abranched refrigerant circuit 70.

An indoor unit 40 with a plurality of associated room units eacharranged in a space 15 forms a heat transfer fluid circuit 90. Expressedin other words, one indoor unit 40 each and several associated roomunits 50 together with the pipe conduits connecting the same form a heattransfer fluid circuit 90.

In the illustrated example, an indoor unit 40 together with twoassociated room units 50 each in one of two larger rooms 15 arranged atthe bottom left in FIG. 1 forms a heat transfer fluid circuit 90. Afurther indoor unit 40 together with four room units each in one of foursmaller rooms 15 arranged on the right in FIG. 1 forms a further heattransfer fluid circuit 90. In the example shown in FIG. 1 a third indoorunit furthermore is arranged in the large space 14 and provided for itsdirect air conditioning without use of an associated heat transfer fluidcircuit.

The air conditioning system is provided for an air-conditioning of thespaces or rooms 14, 15, in particular for cooling and/or heating theindoor air in the rooms 14, 15. The outdoor unit 30 is provided andformed to provide cooling capacity in the refrigerant circuit 70 or towithdraw heat from a refrigerant in the refrigerant circuit 70 in acooling mode, and to supply this heat to an environment of the building10 (in particular at a higher temperature level) by means of a heatexchanger. Alternatively or in addition, the outdoor unit 30 is formedto withdraw heat from the environment of the building 10 in a heatingmode and to provide this heat (in particular at a higher temperaturelevel) in the refrigerant circuit 70 or via the refrigerant circuit 70at the indoor units 40. The outdoor unit 30 and the refrigerant circuit70 can be formed to provide cooling capacity and heating capacity at thesame time. In particular a part of the indoor units 40 is in a coolingmode and another part of the indoor units 40 is in a heating mode.

Each indoor unit 40 is formed to withdraw heat from the associated heattransfer fluid circuit 90 or the large space 14 and supply it to therefrigerant circuit 70 in a cooling mode, or to withdraw heat from therefrigerant circuit 70 and supply it to the associated heat transferfluid circuit 90 in a heating mode. For this purpose, each indoor unitin particular comprises a heat exchanger for transferring heat betweenthe refrigerant circuit 70 on the one hand and the associated heattransfer fluid circuit 90 or the indoor air of the large space 14 on theother hand.

Each room unit 50 is provided and formed to withdraw heat from theindoor air of the associated space 15 and supply it to the associatedheat transfer fluid circuit 90 in the cooling mode, or to withdraw heatfrom the associated heat transfer fluid circuit 90 and supply it to theindoor air of the associated space 15 in a heating mode. For thispurpose, each room unit 50 in particular comprises a heat exchanger forexchanging heat between the heat transfer fluid circuit 90 and theindoor air of the associated space 15.

The air conditioning system can be arranged in a ship or another vehiclerather than in a stationary or mobile building 10. The outdoor unit 30can be formed to exchange heat between the refrigerant circuit 70 andwater, ground water or another underground of the building rather thanto exchange heat between the refrigerant circuit 70 and ambient air.Examples for the configuration of the air conditioning system aredescribed with respect to FIGS. 2 and 3.

FIG. 2 shows a schematic representation of an air conditioning system 20which—similar to what has been shown above with reference to FIG. 1—isusable in a stationary or mobile building, a ship or another vehicle. Byway of example, the air conditioning system 20 is shown with an outdoorunit 30, a first indoor unit 40 (shown at the top in FIG. 2) to whichthree room units 50 are associated, and a second indoor unit 40 (shownat the bottom in FIG. 2) to which two room units 50 are associated. Thenumber of the indoor units 40 and the number of the room unitsassociated to each indoor unit 40 can differ distinctly from therepresentation in FIG. 2.

For better clarity of the representation in FIG. 2, only one indoor unit40 and one room unit 50 each are provided with several referencenumerals.

The outdoor unit 30 comprises a compressor 32, which in particular isdriven by a three-phase AC motor with adjustable speed not shown in FIG.2, in order to generate an adjustable refrigerant flow. Furthermore, theoutdoor unit 30 comprises a first heat exchanger 34 for transferringheat between a refrigerant and ambient air, water or another medium. Thefirst heat exchanger 34 in particular is provided with an axial fan forcirculating ambient air. Furthermore, the outdoor unit 30 comprises acontroller 38 for controlling the compressor 32. The controller 38 inaddition can be formed to receive signals from sensors for detectingtemperatures, pressures, flow rates or other measurement values, whichare not shown in FIG. 2, and to control one or more fans of the firstheat exchanger 34, valves or other actuators.

Each indoor unit 40 comprises a controllable throttle valve 42, inparticular an electronic expansion valve, a second heat exchanger 44, acirculation pump 45, a reservoir 46, a controller 48 and a temperaturesensor 49. By means of fluid lines 71, 72, the throttle 42 and thesecond heat exchanger of the indoor unit 40 are connected with thecompressor 32 and the first heat exchanger 34 of the outdoor unit 30 andtogether with the same form a refrigerant circuit 70.

The controller 48 of each indoor unit 40 is connected with thecontroller 38 of the outdoor unit 30 by means of one or more signallines 78 for transmitting electric, optical and/or other signals. Thesignal line 78 in particular is formed as point-to-point connection oras bus which simultaneously couples the controllers 48 of several or allindoor units 40 with the controller 38 of the outdoor unit 30.

A room unit 50 each comprises a control valve 52, a third heat exchanger54, a controller 58 and a temperature sensor 59. The control valve 52and the third heat exchanger 54 of a room unit 50 each are connectedwith the second heat exchanger 44, the circulation pump 45 and thereservoir 46 of the associated indoor unit 40 by means of heat transferfluid lines 91, 92 and together with the same form a heat transfer fluidcircuit 90.

The controller 58 of each room unit 50 is coupled with the control valve52 and the temperature sensor 59 of the room unit 50 and by means of oneor more signal lines 98 for transmitting electric, optical or othersignals with the controller 48 of the associated indoor unit 40. Thesignal line 98 in particular is formed as point-to-point connection oras bus for coupling the controller 48 of an indoor unit 40 with thecontrollers 58 of several or all associated room units 50.

Other than shown in FIG. 2, the signal lines 78, 98 can extend differentfrom the refrigerant lines 71, 72 or heat transfer fluid lines 91, 92shown in parallel in FIG. 2 and/or have another topology. In particular,all controllers 38, 48, 58 of the outdoor unit 30, of the indoor units40 and the room units 50 can be coupled by means of a single unbranchedor branched bus or by means of several busses which are split incontrast to the representation in FIG. 5.

The controllers 38, 48, 58 together form a control means for controllingthe air conditioning system 20, in particular the compressor 32, thethrottles 42, the circulation pumps 54 and the control valves 52. Thecontrollers 38, 48, 58 in particular are formed to control the airconditioning system 20 in dependence on indoor air temperatures beforeand/or after the exchange of heat each with a third heat exchanger 54,on temperatures in the refrigerant circuit 70 and in the heat transferfluid circuits 90, on an outside temperature or a temperature of anotherheat reservoir with which the first heat exchanger 34 exchanges heat, onsetpoints of indoor air temperatures which are detected at userinterfaces, and on other parameters.

When the sum of the cooling capacities provided at all room units 50falls below a minimum value of the capacity to be provided by theoutdoor unit 30, which is specified by properties of the outdoor unit30, the compressor 32 can be operated in a clocked manner. Thecompressor 32 is switched on and off periodically or aperiodically. Thecooling capacity provided at the second heat exchangers 44correspondingly varies with time. Due to the inertia or the thermalcapacity of the heat transfer fluid circuits 90, this variation of thecooling capacity provided at the second heat exchangers 44 has no or anonly weakly perceptible effect on the cooling capacities provided by theroom units. The thermal inertia or the thermal capacity of the heattransfer fluid circuits 90 each is increased by the reservoir 46.

In the schematic representation in FIG. 2, all indoor units 40 are equaland all room units 50 are equal. Other than shown in FIG. 2, the indoorunits 40 can differ from each other, for example by differentlydimensioned components. Furthermore, the room units 50 can differ fromeach other, for example by differently dimensioned components.

FIG. 3 shows a schematic representation of a further air conditioningsystem 20 which in some features and properties resembles the airconditioning system shown above with reference to FIG. 2. In contrast toFIG. 2, there is only shown a section of the entire air conditioningsystem 20. Possible continuations of refrigerant lines 71, 72, 73, heattransfer fluid lines 91, 92 and signal lines 78, 98 beyond theillustrated region are indicated by broken lines. In the following inparticular those features and properties are shown in which the airconditioning system of FIG. 3 differs from the air conditioning systemshown above with reference to FIG. 2.

In the air conditioning system shown in FIG. 3 the outdoor unit 30 isconnected with each indoor unit 40 by means of three refrigerant lines71, 72, 73. In particular the flow line of the throttle 42 of eachindoor unit 40 is connected with the outdoor unit 30 by means of a firstrefrigerant line 71. The return line of the heat exchanger 44 of eachindoor unit 40 is connected with the outdoor unit 30 by means of secondrefrigerant lines 72, 73.

Between the return line of the second heat exchanger 44 on the one handand the second and third refrigerant lines 72, 73 on the other hand amode switching means 76 each is arranged. The mode switching means 76can be integrated into the indoor unit 40 or be formed as separate,spaced unit connected with the associated indoor unit 40 by a fluidline. The mode switching means 76 each in particular comprises one ormore valves by means of which the return line of the second heatexchanger 44 alternatively is connected with the inlet of a compressor32 of the outdoor unit 30 (cf. FIG. 2) via the second refrigerant line72 or via the third refrigerant line 73 and a circulation pump in theoutdoor unit 30 with the first refrigerant line 71.

Via the signal line 78 or in some other way, the mode switching means 76is connected with the controller 48 of the associated indoor unit 40and/or with other components 38, 48, 58 (cf. FIG. 2 of the controlmeans). The mode switching means 76 allows switching between a coolingmode and a heating mode. When an indoor unit 40 operates in the coolingmode, heat is transferred from the associated heat transfer fluidcircuit 90 to the refrigerant circuit 70. When an indoor unit 40operates in the heating mode, heat is transferred from the refrigerantcircuit 70 to the associated heat transfer fluid circuit 90. Within theair conditioning system 20, one or more indoor units 40 can be in thecooling mode and one or more other indoor units 40 can be in the heatingmode at the same time.

LIST OF REFERENCE NUMERALS

-   10 building-   12 outer wall of the building 10-   14 space in the building 10-   15 space in the building 10-   20 air conditioning system-   30 outdoor unit of the air conditioning system 20-   32 compressor of the outdoor unit 30-   34 heat exchanger of the outdoor unit 30-   38 controller of the outdoor unit 30-   40 indoor unit of the air conditioning system 20-   42 throttle of the indoor unit 40-   44 heat exchanger of the indoor unit 40-   45 circulation pump-   46 reservoir of the indoor unit 40-   48 controller of the indoor unit 40-   49 temperature sensor of the indoor unit 40-   50 room unit of the air conditioning system 20-   52 control valve of the room unit 50-   54 heat exchanger of the room unit 50-   58 controller of the room unit 50-   59 temperature sensor of the room unit 50-   70 refrigerant circuit-   71 refrigerant line (high pressure) in the refrigerant circuit 70-   72 refrigerant line (low pressure) in the refrigerant circuit 70-   73 refrigerant line (low pressure) in the refrigerant circuit 70-   76 mode switching means-   78 signal line between outdoor unit 30 and indoor unit 40-   90 heat transfer fluid circuit-   91 heat transfer line in the heat transfer fluid circuit 90-   92 heat transfer line in the heat transfer fluid circuit 90-   98 signal line between indoor unit 40 and room unit 50

1. An air conditioning system for an air-conditioning of spaces,comprising: a compressor for compressing a refrigerant in a refrigerantcircuit, wherein the air conditioning system is formed for a variablerefrigerant volume flow; a first heat exchanger for exchanging heatbetween the refrigerant and a heat reservoir; a plurality of throttlesfor expanding the refrigerant; a plurality of second heat exchangers forexchanging heat between the refrigerant and a heat transfer fluid in oneassociated heat transfer fluid circuit each; a reservoir for the heattransfer fluid, to increase the thermal capacity, in each heat transferfluid circuit; a plurality of third heat exchangers which are arrangedin one associated space each, for exchanging heat between the heattransfer fluid and indoor air of the associated space; wherein athrottle and a heat transfer fluid circuit with a plurality of thirdheat exchangers are associated to a second heat exchanger; and a controlmeans for detecting a total demand for cooling or heating capacity andfor controlling the compressor between a predetermined minimum capacityand a predetermined maximum capacity, wherein the control means isformed to temporarily switch off the compressor, when the total demandfor cooling or heating capacity falls below a predetermined thresholdvalue.
 2. The air conditioning system according to claim 1, in which thecompressor and the first heat exchanger are arranged in an outdoor unitoutside a building or a vehicle or at an external border of a buildingor a vehicle, and one throttle each and an associated second heatexchanger are arranged in an indoor unit.
 3. (canceled)
 4. The airconditioning system according to claim 1, furthermore comprising: atemperature sensor in the heat transfer fluid circuit.
 5. The airconditioning system according to claim 1, in which no heat exchanger isprovided for dissipating cooling or heating capacity of the refrigerantto a medium other than the heat transfer fluid.
 6. The air conditioningsystem according to claim 1, in which one throttle is controllable. 7.The air conditioning system according to claim 6, in which an indoorunit is connected with the outdoor unit by means of three fluid linesand formed to withdraw heat from the heat transfer fluid in a coolingmode and supply heat to the heat transfer fluid in a heating mode. 8.(canceled)
 9. The air conditioning system according to claim 1, whereinfor driving the compressor a three-phase AC motor with adjustable speedis provided.
 10. (canceled)